Hepatitis C virus (HCV) is a (+)-sense single-stranded RNA virus that is a major cause of non-A, non-B hepatitis worldwide. A large percentage of people infected with HCV develop chronic liver disease. This chronic hepatitis C infection, in turn, puts them at high risk for developing serious liver diseases such as liver cirrhosis, hepatocellular carcinoma and terminal liver disease leading to death.
Compounds having an (S)-N-cyclopropylamino-1,2-dioxoalkan-3-ylamide group, for example an (S)-N-cyclopropylamino-1,2-dioxohexan-3-ylamido group, have been shown to be useful both for the treatment of hepatitis C and related disorders, and as cathepsin S inhibitors. See, for example, U.S. Patent Application 2007/0054864 and WO2006/102243, the complete disclosures of which are hereby incorporated by reference. Accordingly, it would be desirable to have a facile synthesis of common intermediates useful in the preparation of such compounds, particularly a synthesis suitable for large scale preparation of this and similar intermediates.